My 4yo will sometimes say her heart hurts and that she feels it beating. she says it when she's at rest. has an innocent murmur and normal echo 2yrs ?

Heart beats: she could be experiencing palpitations and would not have been evaluated completely by her ECHO. She needs an evaluation for this.

Many are heartburn: Communicating with a 4 yo is often fraught with translation problems. Assuming she can reasonably separate the heart from the ribcage/breastbone above & junction of swallowing tube/stomach beneath is a stretch.Some adults can't. She can focus on the heart and perceive it beating, but that does not mean it is the problem.Many just have heartburn/reflux and would improve with a simple diet changes.